For example, if I make a game and then the player buys a character, then I upload an update just to add new characters, does it affects or deleted that unlocked character? What happen if I change the price or the name or the image of the unlocked character?
As far as I know each item can be wired with in-app purchase by its number set in game whether it's unlocked character or level. Unless you don't change this number everything stays the same. Numbers are given from app store. I think you can change the graphics for it but detailed description of it may be requested by store.
If you add characters don't overlap them. For example i will tell you an issue i've seen. If you have characters : 1,2,3,4,5,6,7,8,9,10 and want to add 2 more, add them as 11,12 under all of them. Don't try to add them in the middle. That way what people already bought will not be the same after update
